Method of making inflated rubber articles.



F. T. ROBERTS.

METHOD OF MAKING INFLATED RUBBER ARTICLES.

Llfi fi aa- Patented Jul 13, 1915.

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APPLICATION FILED OCT- 2, 193.

F. T. RGBERTS. METHOD OF MAKING HQFLATED RUBBER ARTICLES:

APPLlCATlGPl FILED OCT. 2, i913. hmfi fi fio Pamnm July 13, 1915.

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mura STATES arana orrroa FRED THOMAS ROBERTS, or TRENTON, NEW JERSEY,'nssreuoa or FIFTY our: ownnonmmnrnsmo aALrH H. RosENF Ln, or CLEVELAND,0111c.

mn'rnon or MAKING INFLATED RUBBE ARTICLES.

Specification of Letters Patent.

' PatentedJuly 113, 1915.

Applicationfiled October 2, 1913. Serial No. 793,025.

I To all whom it may concern: Beit known that I, FRED THOMAS ROB- ERfrs,a citizen of the United States, residing atTrenton, in the county ofMercer and State of New Jersey, have invented certain new and usefulImprovements in Methods of Making Inflated Rubber Articles and I dodeclare the following to be a full, clear, and exact description oftheinvention, such as will enable others skilledin the-art to which itappertains. to make and use-the same. M i

This invention relates to methods of making rubber articles, or 'thoseofacomposition containing rubber to such an extent that-the article may besubjected to the curing or vulca'nizing process; and more particularlyit relates to' the method ofuniting the several partsof a hollow rubberarticle and meanwhile inflating it so-that when finished' it issubjected to greater internal pressurethan the atmosphericpressure on";the exterior. I r Heretofore it-has been the practice in makingarticles of this character,"sueh as rubber tennis balls and the like, tocement togetherthe sections which are-to consti-' tute the ballwith acertain amount are, pansible substance, 1 usually V ammonia powder, intheinterior, and a'soft rubberbutton secured at some point on the inner;face of the rubber. QWhensuch astructure was ,vulcanized' the heatvaporized the amv monia, powder or' other J expansiblematerial and.created a suficient internal pressure to enable proper'vulc'anization,"but, after vulcanization-and the cooling of the ball itI was necessary {to inject fluid under pressure to inflate the ballfor-use. This was. ac c0m.

40 plished' by piercing the ball through .the' :button with a-hollowneedle and blowing air through-such needle,- Theammonia and. otherexpansible substances commonly used."- ;within the ball hadadetrimental'chemical effect onthe rubber, rendering it brittle: andliable to'crac'k. The'sealing, by eans of: the soft rubber plug, wasfrequently effective, and such balls gradually leaked" air and losttheirresilience. The constant leakage of the air.tlirough the plug .sealfcaused the ball to shrink which was 'par- I "ticularly disadvantageousin, tennis balls,

, forthe shrinkage caused the uover'to be'.

come .loose,'.resulting in "the inmiediate de-j'ffteriorati'on oftheba'll play. f

short periods.

was. so-wea'k'that it 'often'became displaced age has been so bad thatit has become customary fordealers to return to the manufacturers forre-inflation, balls which have. remalned unsold for variouscomparatively The interior rubber plug, moreover, has the effect ofthrowing the ball out of balance-and causing it to return or bounceirregularly when struck or land lng'directly opposite the plug, whichlatter I feature is noticeable inaccurate playing; Occasionally, in themanufacture, the ,hollow needle was inserted at some other point thandirectly through the plug and this immediately destroyed the ball.

-Hereto fore also vit has been common' to make balls of this kind inparts such as halves, and unite the halves by curingtheir edgestogether; but this" process produced an internal rib or seamwhichthickened the wall of the article along the meeting lines between. itsparts or halves, and inithe case of a tennis ball-prevented itfromirebounding as accurately'if it'st'ruok a racket or the t able,whereas whatevermaterial'exuded externally along the meeting lines orseams could be cut-01f later' sothat the walls would not be .thickenedonthe exterior. 'Thefseal in "of thevneedle hole was also objectionab e,becaus in addition to-thefaet thatfth'e' seal-was not always reliable orthe button I if theball'were struck a sudden blow, tw'o kindsofrubberwere employed, and the cement fsealing the hole made the wall a. lit tlethicker-for denser at this point,-and the same objections arose as arepointed out above. I, The object] 'f the present invention isto make ahollow "inflated article"'(.I'v de-- scribe it hereinafter-withreference to a ten-1 nis 'ball," excepting for the felt or fabric coverappliedlater) in parts such asthalvs" .which are connected? along'theirmeeting edges in such away that the seam or rib produced in the actofcuring said edges togetheris entirely onthe exteriorof the ball, andthereiere it may be ground or cut ofi later and the wall will be of onethickness anddensity-throughout, This object is carriedfout by'means ofan apparatus forms the. subject matter of a'coinpanionfapj 116 plicationfiled herewith and bearing Serial Number 793,026 and by the methoddescribed below and illustrated in the accompanying drawings wherein--Figure 1 is'a sectional view through a two-part mold such as is employedby my method for making each half of the ball, the members of; the moldin this view being shown in position about to be forced toward eachother; Fig. 2 is a similar section showing the members after they havebeen forced toward each other for a considerable distance; Fig; 3is"a'sectional View through the partly cured rubber part or halfproduced by this mold; Fig. 4 is a section through the flask orpressused in my improved method, the'right side of this view showing twoof the halves of Fig. 3' in place in the blocks of said press; "and Fig.5 is a similar section of the right hand portion of Fig. 4 showing theblocks as brought together to unite said halves; Fig; 6 is a'ver'ticalsectional view through. the apparatus into which the flask is introducedfor finishing the curing process, and Fig. 7 is a similar section-theplates of said flask being separated in the former view and broughttogether in the latter View; Fig. 8 is a sectional detail of thefinished part, showing at the sides thereof in dotted lines the flangeswhich are later trimmed off by any suitable means; Fig. 9 is a sectionalview of a slightly modified form of apparatus for handling the flask,and Fig. 10 is a. plan view of the flask alone.

According to my improved method a block of rubber material 1 isintroduced between a female die 2 and a male die 3 as in Fig. 1, thesedies are brought toward each other as shown in Fig. 2, and then they areforced yet farther toward each other so that the part 4 is produced asshown in Fig. 3, the same being herein illustrated as one-half of aspherical tennis ball having a surrounding flange 5 which it will beobserved is a little thinner at its outeredge than where it unites withthe wall of the partthis difference in its thickness being produced bythe shapeof thev male die at the pomt '6. The part shown in Fig. 3 isnot completely cured, and the object of the present mvention is toassemble two of these parts and I seal their flanges together whilesimultaneinterior of theball being formed.

ously introducing compressed air into the The flask or press employed incarrying.-

out my improved method is best seen in plan view in Fig. 10- whichindicatesthat 1t may have cavities for making or pressing four balls atonce, although of course there could be a greater orlesser number ofsaid cavities, and in fact the I mechanical deta ls are not essential tothe method to be described. The

upper plate 10 is herein shown ashaving upright sockets 11 into. whichslide dowel pins 12 which are screwed as at 13 onto sockets in the lowerplate 14 and rise above the upper face of the same, and the lower platehas a threaded central hole 15 engaged by the, threads of a screw 16which is rotatably mounted within a smooth hole 17 in the upper plate 10and projects below the lower face of this plate as seen. The screw is'swiveled in this plate by any suitable means, preferablyby having aflange 18 around it overlying the plate and held in place by a faceplate or keeper 19 removably mounted on the plate 10 by screws 20, andthe upper end of the screw 16 is squared as at 21. .It follows thatwhenany suitable key is applied to this squared portion and turned in theproper direction, the plates 10 and 14 will be brought together, andthey will be of the flaskor press are now brought together by applying akey to the squared portion 21 of the screw 16 and turning the latter inthe proper direction, and the entire flask may then be inserted into asuitable vulcanizer and treated with heat (by steam or otherwise) tocomplete the curing or vulcanization of the rubber in a well-knownmanner.

Referring nowto Sheet 2 of the drawings, which illustrates an apparatusfor usein carrying out the method of this application,

the numeral 30 designates a tank or a chamber of good size, shown ascontaining a table or other support 31 on which the flask may lie.Through the walls of this tank are steam inlet and air inlet pipes 32and 33 controlled by suitable valves, and anoutlet pipe 34 also suitablycontrolled. .The cover 35 for the tank or chamber-30 has fixed throughit a tubular guide 36, preferably surrounded by packing 37, and theguide is While its upper end may be held rigidly upon the cover by meansof ajyoke 39.

Mounted throughout thelength of the guide is a key 40 having a threadedlowerend engaging the threads 38 and any suitable form of handle 41-atits upper end, and the lower extremity of this key has a socket 42 whichis squaredfor the reception of the squared .upper end 21 of the screw16. s

With, an apparatus; as thus eonstructed, the carrying out of my methodis as follows,

internally threaded as at 38 at its lower end after. the parts 4 shownin Fig. 3 have been made: Two of said parts in their semi-cured 85 ofthe article-are pressed-into contact and I two mating blocks 23 when theplates and condition are placed in the cavities 24-of 14 of the flaskstand remote from each other;

closes and'r'etains, air 'within the ball beingand if said plates haveseveral pairs of said blocks, several tennis balls can be madesimultaneously. The cover of the tank or chamber 30 is then removed andthe open flask placed on the table or support 31, after Jvhich the coveris restored and the key screwed down by its handle 41 until its socket42 engages the squared upper end 21' of the screw 16. The pipes 32 and34. are ,now closed, the air pipe 33 opened, and airy under pressure isadmitted to the interior of the tank, whence it of course passes intothe cup shaped parts 4 heldfin the flask. The 'handle 41 isnowmanipulated to turn the key and the screw 16, and the threads of theo latter cause the upper plate to move down- 2 iwith each other. Thisbrings the edges of ward'until the blocks 23 come into contact the wallsof the parts 4 into contact andin formed. It also compresses theprojecting flanges5 against each other, the surplus material beingpressed outward into the channel 25 and finally even upward and downwardinto the gutters 26 which are formed in the upper and lower channels asabove described. But none of the surplus material in the flanges will bepressed into the in-' terior of the spherical article thus being made,because said article contains air under pressure and the inner edges ofthe flanges-- that portion where they unite with the walls united witheach other so that the internal air pressure is maintained. The air,pipe 33 is now closed, the outlet 34 opened, and

steam admitted at 32 to complete the curing the wall of whichis ofuniform thickness and density throughout and which will have no ridge onits interior or exterior wherethe seam occurs betweenv its two members.Thls results from the fact that said members are pressed firmly togetherwhile they are in a semi-cured state, within a chamber which is filledwith air under considerable pressure,

' and the pressure is not lowered until the members have-been unitedair-tight.

In" the modified form of the. apparatus shown in Fig. 9, the centralscrew 16 and the threads 15 of the lower plate are omitted,

and the dowel-pin sockets in this plate are surrounded by recesses 50within whlchj rest the lower ends of coiled springs 51 that surroimd thedowel pins as shown. In place of the screw and key for forcing the twomem- After the press has been placed on the stand or table ,Within thetank or chamber, its

plates being normally separated. by the springs 51, the cover is put inplace and the ball 53 at the lower end of the plunger is entered intothe socket 54. The weight 59 will now depress the upper member againstthe tension of the springs 51 and will cause the two plates to bebrought together so that the operation. above described is carried out.This, however, is but another apparatus for carrying out the generalidea set forth, and in the present application I do not wish to belimited to the apparatus employed,

I have spoken throughout this specification of the use of air forinflating the balls or other hollow articles, but reserve the right toemploy any preferred fluid, and the same may be supplied to the tank inhot or cold state.

It has been convenient. to describe the process with particularreference to balls which are permanently inflated, and such adaptationof the invention is an important one, but the process is applicable tovarious other forms of hollow articles, and it is ob vious that it maybe employed where the inflation is only temporary and is used to securea more effective vulcanization of the surface and welding of the seamsduring .vulcanization. After the article is produced by my process theinternal air pressure may be released by removing a section of thearticle whenever the use of the articles demands a hollow Lin-inflatedbulb or structure -of any sort. I

It should be noted that, by my system of supplying air pressure,suflicient pressure may be caused in the interiorof the article toeffectively compress the rubber against .the wall of the moldduringvulcanization and to effectively weld the seam, and to stretch ordistend the article when released from the mold, this distention beingparticu'larlyimportant in playing balls to gave them the desiredresilience or livel-iness.

I have described and illustrated'the use of steam for completing thecuring process within the tank, but reserve the right to employ anysuitable means or method whlch may. be carried out withln a closedchamber where the articlebeing cured can be subjected to pressure. Infact, I do not wish to be limited at all to the apparatus em- 7 armployed for carrying out the method set forth 1n this specification, asany suitable apparatus may be used for homogeneously uniting the meetingedges of the walls of two 879,556, filed December 29, 1914.

What is claimed as new is:

v 1. The herein describedmethod of making hollow rubber articles whichconsists 1n' first forming them in cup-shaped parts whereof each has anoutwardly projecting flange around its open mouth, then bringing saidparts together edge to edge in a chamber wherein they are subjected to'compressed air, then pressing said flanges against each other andmeanwhile subjecting them to the curing process, and finally trimmingOfftllflfitihgGS.

" n described method ofmakibber balls which consists in first formmg thesame in cup-shaped halves whereof each has around its mouth a radiallyprojecting flange thinner at its outer edge than where it unites withthe body of the half, then bringing the halves together edge to edge ina chamber wherein they are subjected to compressed air internally,

vthen pressing the edges against each other and the flanges into contactwith each other and meanwhile subjecting them to the curing processwhile the air pressure is maintained in the ball, then reducing the airpressure in the chamber and removing the balls from the mold, andfinally cutting off I the surrounding flanges.

3; The herein described method of making hollow rubber articles whichconsists in first forming the articles .in cup-shaped parts and in asemi-cured condition. then placing said parts in a chamber wherein theyare subjected internally to compressed air and bringing them togetheredge to edge,

then withdrawing the pressure from the chamber outside the parts, andthen concluding the curing process while the internal pressure ismaintained.

4. The herein described method of making hollow rubber articles whichconsists of forming them in cup-shaped parts, then niting. said partstogether edge to edge in chamber containing an enveloping body of'compressed air, then subjecting the parts.

Y to I the curin g process.

5-. The herein described method of makgiiiiflatecl rubber balls whichconsists in first placing two cup-shaped halves in cavities in a pair ofblocks, then bringing the blocks together in a chamber wherein they aresubjected to compressed air internally,

dition.

articles consisting of inaking th e" arti in parts, uniting the partswithin,,an enyelop ing fluid under pressure, and removing the articlefrom the enveloping fluid. i

7 The method of making infiated rubber articles consisting in making thearticle in concave parts, bringing such parts itegether edge toedgeavith theircoiniavi.

facing each other within an enveloping flu under pressure and after themeeting-edges hare adhered relieving the article-from the eX- ternalpressure.

8. The method of making liollow rubber. articles consisting in submittsuch article in an nnclosed condition to an en'weloping fluid underpressure, closing it whilir under such pressure, and thereafterrulcanizing it while the pressure is maintained within it.v

9. The method of 'making inflated rubber articles consisting in formingthe articles in" parts and semi-curing them, then bringing said partstogether edge to e 'lge in a chamber wherein they are subjected tocompressed fluid and then externally holding them in this condition andremovii them from the chamber and siiliijecting them to heat while soheld. a

10. The metl'uid of making"inflated arti-- cles of material imperviousto ordinary air,' j'

' ul lFJ of materialimpervious to ordinaryair consisting of firstsubmitting the article in a. semi-cured condition and'i'iiiclosed to'asurroui'iding atmosphere under pressure, closing said article whileui'ii'ler such pressi'lre .reliei'ing the pressure on the outside of thearticle while holding the article closed, and completing the curingofthe article by heat while it is in such closed con- 12. Themethod'ofmaking inflated hollow articles consisting in submitting them iii-anlated rubber LIL/16,523

. cles impervious to ordinary air consisting in causing an envelopingair pressure both outside of and within the article while it is in anunclosed condition, then closing it uponsuch air so as to retain the airpressure within it without the necessity of pressure producingchemicals, then relieving the air pressure on the outside of the closedarticle and then treating the closed article to cause a secure junctionwhere closed.-

15. The method of making inflated rubber articles consisting of makingthe article in semi-cured parts, bringing such parts together within anenveloping atmosphere of air -under pressure, holding the partstogether, therebyconfining the compressed air within the article and inthis condition vulcanizing the article causing it to have the originalair under pressure when completed.

16. The herein described method of sealing compressed air within ahollow rubber article, consisting in subjecting the article T1111 anunclosed condition and a condition ',;adapted for curing to anenveloping at mosphere of air under pressure, then closing the articlewithin such atmosphere to entrap compressed air within it, continuing tohold the article closed with such air engreigped, and curing the articlewhile so 17. The method of making inflated rubber articles consisting informing the articles in parts, bringing such parts together in anenveloping body of fluid under pressure and vulcanizing the articlewhile the same fluidis confined within it.

18. The method of making inflated rubber articles consisting in formingthe article in parts, bringing such parts together within a chamber towhich compressed airis supplied from the outside, whereby such air isentrapped within the article; and vulcanizing the article while the sameair is confined within it.

19. The process of manufacturing rubber balls consisting in moldinghollow hemispherical sections, partially curing said hollowhemispherical sections, bringing the edges of two such hollowhemispherical sections into contact and uniting them within a fluid bodyunder pressure, continuing to hold them united, and finally vulcanizingthe sphere thus formed and so held.

In testimony whereof I have hereunto set my hand in presence of twosubscribing witnesses.

v Flt-ED THOMAS ROBERTS.

Witnesses:

J. RALPH HOGE, J. A. GRIESBAUER.

